1. Technical Field
The present invention relates to a sensing device that irradiates light on a subject and that receives the reflected light thereof, and an electronic apparatus.
2. Related Art
There are biometric authentication devices and image scanners in which the image of a subject is read by arranging the light emitting unit and the light receiving unit on the same side with respect to a subject (for example, a finger, a manuscript, or the like) that is placed on a reading region, irradiating light on the subject from the light emitting unit, and receiving the reflected light thereof with the light receiving unit. For example, a biometric information acquisition device 50 that obtains the vein image of a finger 100 by irradiating exit light (near-infrared light) from a light source 6 on the finger 100 by a plurality of reflection faces 11 that are formed on the back face of a light-guide plate 3 and receiving the reflected light from the finger 100 on a light receiving element 1 that includes a plurality of pixels PX is described in JP-A-2009-172263.
However, in the biometric information acquisition device 50 described in JP-A-2009-172263 is the light-guide plate 3 that guides the exit light from a light source 6 with a greater light amount than the reflected light on a light path of the reflected light that is incident on each pixel PX (on a straight line that extends in the vertical direction from each pixel PX). Further, a portion of the exit light from the light source 6 leaks out to the light receiving element 1 side by passing through a low refractive index layer 21 or a reflective layer (semi-reflective layer) 40 that are formed on the back face side of the light-guide plate 3. It is therefore not possible to receive the reflected light from the finger 100 on the light receiving element 1 with high precision. Further, there was a problem that the thickness of the biometric information acquisition device 50 increased due to the light-guide plate 3 or a light blocking layer 2.